Acyl derivatives of glyceraldehyde-3-phosphate dehydrogenase.

Acetyl phosphate and 1,3-diphosphoglycerate react with glyceraldehyde-3-phosphate dehydrogenase to form relatively stable enzyme substrate compounds. These compounds appear to be thiol esters, and their properties indicate that they are intermediates in the catalytic activity of the enzyme: they undergo hydrolysis and arsenolysis in the presence of DPN and are reduced by DPNH to form aldehydes. These results are in agreement with the mechanism previously proposed for the oxidation of aldehydes in which a thiol ester formed on the enzyme, with concomitant reduction of DPN, is split in the presence of phosphate to acyl phosphate and regenerated enzyme.